Perhaps for many people the term decibel doesn't mean a lot. So for starters let's take a look at a few dictionary definitions.
The Cambridge English dictionary defines it as "a unit for measuring the loudness of sound", while the Collins dictionary describes it as "a unit of measurement which is used to indicate how loud a sound is". And for the more technical, the Merriam-Webster dictionary defines it in one way as "a unit for expressing the ratio of the magnitudes of two electric voltages or currents or analogous acoustic quantities equal to 20 times the common logarithm of the voltage or current ratio". Umm...
Here is an excellent video explanation by the celebrity YouTuber, Linus. One important fact you'll hear is that our ears don't hear sound pressure in a linear fashion. Linus also mentions that Wikipedia has a chart
that you can reference next time you see a loudness rating in decibels so that you have some context for interpreting published sound ratings and their meaning.